Concentration of sulfuric acid



v CONCENTRATION 0F SULPHURIC ACID.

APPLICATroN FILED mm2?, 1919.

E Umdwzser Patemasapt. 21, 1920; f

naires stares .ANTON CHRISTIAN BOHRE, DECEASED, BY KATHARINA CHARLOTTE BOI-IRE, EXECU- TRX, 0F BERGEN, NORWAY, ASSIGNOR TO NORSK HYDRO-ELEKTRISK KVAELSTO- FAKTIESELSKAB, OF CHRISTIANA, NORWAY.

CONGENTRATON\OF SULFURIC ACID.

Application filed March 27, 1919.

To all whom it may concern.:

lle 1t known that ANTON CHRISTIAN Borrnn, deceased, did invent certain new and 'useful lmprovements in the Concentration of Sulfuric Acid, and that l, KATHARINA CHARLOTTE BOHRE, of Bergen, Norway, his widow and executor, do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the saine, reference being had to the accompanying drawings, and to letters or figures of reference thereon, which form a part of this specification.

This invention relates to the concentration of sulfuric acid by means of heated gases and has for its object a process as well as an apparatus which allows of carrying such concentration into effect by simple means and in an eiiicient manner.

lt has already been suggested to concentrate sulfuric acid directly by means of hot nitrous gases by passing the gases through an acid-proof tower charged with, dilute sulfuric acid. As known this method. however, has not met with success and it has not been possible to'make this concentration method practically useful. This is due among other reasons to the fact that the subsequent absorption of the nitrous gases is rendered difficult by the moisture taken up in the gases, said moisture being condensed in the subsequent absorption systeimy whereby the temperature in this latter is considerably raised and a very ineiiicient absorption results.

The degree of 'saturation of the gases as regards ,the moisture being comparatively low it is difficult to bring about the condensation of moisture by means of cooling. Moreover it is not possible to employ the hot gases directly with the high temperature prevailing in the same on their leaving the electrical furnaces viz. about 1000--1200 (l. because the sulfuric acid in Contact with the gases qf such high temperatures is liable to be decomposed producing fumes which it is very diiiicult to absorb. lt has therefore been necessary either to dilute the gases with air or to bring the temperature down by other cooling means,

The present invention now has for its ob- Speccation of Letters Patent.

Serial No. 285,674.

ject a process, allowing otv directly using high temperature nitrous gases for the concentration of dilute sulfuric acid and at the same time the gas leaving the system is practically saturated with moisture which can thereupon be removed to the greater part in comparatively small condensation apparatuses before the gases are introduced into the absorption system.

A preferred method of carrying the invention into effect is described in the following by way of example:

A portion of the gases saturated with moisture, which leaves the concentration apparatus is returned and utilized to cool the hot nitrous gases from the electrical furnaces. The quantities are so proportioned, that the quantity of circulating gases ,is sufficient to lower the temperaiture to 50043009' C. A quantity of escape gases which correpond to the supply of hot gases and which are saturated with moisture is at the same' Patented sept. 21, 192e.

A plant for use in carrying this process into effect is diagrammatically illustrated in the accompanying drawing by way of eX- ample:

Hot nitrous gases with a temperature of about 1000o C. are introduced at A. These gases are atB mixed with gases from the upper part of the apparatus in such proportion that the gases' when entering the tower at C have a temperature of 500 C.

The gases saturated with moistureleave -the apparatus at D with a temperature' of about and are introduced into a condenser E. where the greater part of the moisture is separated out. The condensation product consists of a very dilute nitric acid, which is' suitably utilized in the absorption system to which it is supplied instead of water.

By maintaining a circulation of the moist gases from the concentration plant it is made possible to lower the temperature of the nitrous gases suiiiciently to' avoid decomposition of the sulfuric acid and th resulting production of fumes. This is attained without diluting the nitrous gases, which would los v,drm'vloacks connected herewith.

have been the result if ai? hadloeen adde. No1 is it necessary to remove any of the heat contained in thei gases by means of cooling which would have resulted in an increased consumption of gases as well as falle ;`The result j is also attained that the escaping gases are practically completely saturated with mois-- ture',`s that the condensation 0I" moisture may take place. in en apparatus of e Compa?- atvely small sizeu memes 'rent mi' het iifare'aus'gnses having a tempera 15 vtime above SOOO V. 1x1 Contact` with the 'acid te be concentrated, und mixing a portion o the esultng moist gas 'Wi'fcli the eurren; of het nitrous gases. 

